Modular fusion apparatus using disposable core

ABSTRACT

A fusion power generating device is disclosed having a relatively small and inexpensive core region which may be contained within an energy absorbing blanket region. The fusion power core region contains apparatus of the toroidal type for confining a high density plasma. The fusion power core is removable from the blanket region and may be disposed and/or recycled for subsequent use within the same blanket region. The high density plasma produces a large radiation and particle flux on the first wall of the plasma core region thereby necessitating replacement of the core from the blanket region from time to time. A series of disposable and replaceable central core regions are disclosed for a large-scale economical electrical power generating plant.

This is a continuation of application Ser. No. 841,903, filed Oct. 13,1977, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is in the field of fusion power generators, particularlythose utilizing fusion reactors of the magnetic confinement type.

2. Description of the Prior Art

Prior art concepts with regard to utilization of fusion energy for theeconomic production of power have been premised upon an ultimate designof a large scale reactor able to produce the desired power and lasting asufficiently long time to justify the large capital investment requiredto build the reactor. The economics of a large capital investment with along reactor lifetime have been carried over from the fission reactorfield as an inherent basis in the design of economic fusion powerplants. Consequently, plasma temperatures and densities have beenparameterized to yield a maximum wall loading of the first wall (vacuumwall surrounding the plasma) consistent with durability of wallmaterials and a long replacement time which is economically acceptable.Typically, a maximum wall loading of 1-3 MW/m² has been thoughtreasonable with a minimum replacement time of approximately five years.

Consistent with the projected long life of the fusion reactor, theplasma core has traditionally been made large so as to allow large poweroutput with low energy loadings on the first wall as well as for reasonsof plasma confinement in the regimes of traditional interest.Furthermore, the plasma core has traditionally been surrounded directlywith a thick material blanket region to absorb the plasma-generatedneutron energy as well as to protect the large and expensive magneticfield windings surrounding the blanket. These large field windings,required to confine plasma in the plasma core, must be large enough tosurround the plasma core. Traditionally, superconducting magnets havebeen utilized in order to reduce the power required to drive themagnetic coils, and the blanket thus served to remove the coils from theregime of high neutron fluxes and associated radiation damage to whichthe superconductors are susceptible. Such superconducting magnets have alimited magnetic field capability of between approximately 80 and 150kilogauss. The maximum permissible density and temperature of the plasmais in turn dictated by the strength of the magnetic field possiblewhich, because of the foregoing considerations has been limited to themaximum strength available from the superconducting magnets. Thus,traditional fusion device concepts have involved large plasma volumes,thick blankets of large volume, low first wall loadings, and the use oflarge, expensive superconducting magnets placed outside the regions ofthe blanket, plasma core, and any added auxiliary shielding.

In utilizing large volume experimental reactors of the tokamak-type, andin the conceptual design of practical large volume toroidal reactors,ohmic heating inherently plays a negligible role in the process ofraising the plasma temperatures to values of thermonuclear interests.This is true because the current density which can be induced in anytoroidal plasma configuration is proportional to the magnetic fielddivided by the major radius of the torus. For the fields attainable bysuperconducting magnets and the dimensions of traditionally envisionedtoroidal devices, the current density is insufficient to yieldsignificant ohmic heating of the plasma. Thus, in both the experimentaland conceptual designs large sources of energetic beams of neutralparticles have been utilized to provide power to the plasma on the orderof tens to hundreds of megawatts. Neutral beam injection techniquesrequire the utilization of large access ports to the plasma through thesurrounding magnetic structure thus adding to the cost and complexity ofany practical fusion power plant. Additionally, in order to ensureproper beam penetration to the center of the plasma column, operation ofneutral beam injection devices has been limited to plasma densities theorder of 10¹⁴ /cm³.

As experimental fusion devices, blankets have typically not beenemployed inasmuch as they are unnecessary to study many of the basicphysical processes involved in the plasma such as plasma fusionignition, confinement, plasma heating and fusion reaction studies. Thetokamak has provided an experimental tool for testing the feasibility ofplasma confinement and has been the subject of extensiveexperimentation, e.g., see "The Tokamak Approach in Fusion Research" byBruno Coppi et al, Scientific American, July 1972, U.S. Pat. No.3,778,343 and "Tokamak Experimental Power Reactor Conceptual Design",Vols. 1 and 2, ANL/CTR-76-3 (August 1976), all of which documents areincorporated herein by reference. One particular tokamak device, theAlcator, has been designed to achieve large plasma currents with hightoroidal magnetic field strengths. Typically, plasma currents on theorder of 100 kiloamps with field strengths up to 82 kilogauss have beenobtained. In such experimental devices, plasmas with densities up to9×10¹⁴ particles per cubic centimeter with temperatures up to 1 keV havebeen contained. However, the Alcator approach is not typical of themajority of prior art devices which have focused on toroidal devices ofmuch lesser density, larger dimension, smaller magnetic fields and whichrequire extensive auxiliary heating (generally by neutral beaminjection) to strive for plasma ignition temperatures.

The approach of a very high yield, high density and a small compactdevice such as the Alcator has been considered in the prior art aslimited to merely academic interest for purposes of physics studies ofplasma behavior but has not been considered of interest for futureapplications to practical fusion power production.

Another experimental area that has been developed for the magneticconfinement of thermonuclear plasma is embodied in the stellaratorconcept. While in the tokamak, the confining magnetic field is partiallyproduced by external coils and partially by the current induced in theplasma, in a stellarator, the confining field is produced only byexternal coils. Both the tokamak and the stellarator, however, may beconsidered forms of a toroidal plasma confinement device.

SUMMARY OF THE INVENTION

It is an object of the invention to overcome the disadvantages of theprior art by providing a controlled nuclear fusion device for powergeneration.

Another object of the invention is to provide a modular fusion reactorsystem wherein a plurality of fusion power cores, each of relativelysmall size and low cost, are energized to provide a power system. Energyfrom the fusion power cores is absorbed in the core structure and withina surrounding blanket, and the cores themselves may be individuallyremoved from the blanket and replaced by new cores as the coresdeteriorate from high radiation flux damage.

It is another object of this invention to provide a power generatingsystem utilizing a plurality of fusion power cores, each of thetoroidal-type and driven to ignition by ohmic heating techniques.

In accordance with the principles of the invention, a fusion powerdevice is provided and comprises a plasma containment means forcontaining a fusible plasma within a region and a blanket means whichsurrounds a substantial portion of the containment means. The plasmacontainment means is separable from the blanket means and may bereplaced upon excessive radiation damage by a new or refabricatedcontainment means. Means are also provided for feeding the fusible fuelinto the containment means for forming the plasma. A power producingregime of temperature and density may be achieved using ohmic heating aseffected, for example, by e-beam bombardment. Thermal energy extractionmeans are provided for extracting energy from the plasma containmentmeans and/or the blanket means, and means are provided for convertingthe extracted thermal energy into mechanical and/or electrical energy.

The disposable and/or recyclable characteristic of the considered fusionpower core makes the remote handling and maintenance system for itconsiderably simpler and less expensive than those envisioned for aconventional large tokamak reactor where the removal and replacement ofheavy and interconnected components is involved.

The ability to place an easily accessible blanket at the outside of thefusion power core without the encumberance of a surrounding magneticcoil system makes it possible to adopt the simplest and least expensivesystem to breed Tritium.

The absence of a need for easy access to the inside components of thefusion power core makes it possible to adopt a tight aspect ratiotoroidal configuration. This feature, which can also be coupled with theeffects of adopted auxiliary heating systems that tend to produce welldistributed plasma current densities, by enhancing the temperature atthe outer edge of the plasma column, makes it possible to operate theplasma device with a relatively low safety margin against macroscopicinstabilities. This is equivalent to a high degree of utilization ofconfining magnetic field.

The small size and relatively low weight of the fusion core make itsuitable to develop it, unlike the envisioned large size tokamaks, intoone of the elements of a power plant to power or propel a ship, a spacecraft, or any other suitable type of vehicle.

A choice of the appropriate structural materials of the fusion powercore can be made with the objective to decrease their radio-activationto a minimum. For example, aluminum based metals can be considered forthis purpose.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent inreference to the detailed description set forth herein, taken inconjunction with the drawings wherein:

FIG. 1 is a schematic block diagram of a single module showing the majorcomponents thereof together with the various fuel/thermal/electricalinterconnections;

FIGS. 2A, 2B and 2C illustrate a plurality of modules having differentthermal transport embodiments;

FIG. 3 shows a block diagram of a power generating plant in accordancewith the principles of the invention;

FIG. 4 is a top cross-sectional view of a module in accordance with theinvention;

FIG. 5 is a top view of a disk coil utilized in the fusion power core ofthe invention;

FIG. 5A is a side view of the disk coil of FIG. 5;

FIG. 5B is a partial side view of the disk coil taken along line 5B--5Bof FIG. 5;

FIG. 6 is an enlarged cross-sectional view of the fusion power coresimilar to that shown in FIG. 4;

FIG. 7 illustrates a segment of the toroidal shell and disk coils astaken along lines 7--7 of FIG. 6;

FIG. 7A illustrates another embodiment of the toroidal shell and diskcoils in accordance with the invention; and

FIG. 8 is a side plan view of the module of the invention illustratingthe removal of the fusion power core from the surrounding blanket.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates an embodiment of a module 1 of a fusion generatingdevice in accordance with the principles of the invention. A fusionpower core 2 is shown housed within two clamshaped regions 4a and 4b ofa blanket 4. The blanket 4 absorbs radiation emanating from the fusionpower core as a result of the fusion reaction. It is the function of theblanket 4 to absorb such radiated energy which appears mostly asneutrons generated in the fusion reaction. These neutrons could be usedto generate fission in fission plates incorporated as neutronmultipliers in the blanket assembly or simply for the production of heatby neutron slowing and neutron capture reactions. Such heat energy isextracted by means of a coolant passing through conduits 8 which areshown diagrammatically as penetrating the blanket region 4a. The conduit8 may in fact be a plurality of cavities or conduits passing throughboth regions 4a and 4b of blanket 4 and may be of the multiple arterytype so as to cover a large region of the blanket to absorb maximumamount of heat energy. The fluid conduit 8 passes to heat exchange meansand pump means indicated at 10. The blanket material may, for example,be composed of graphite, fluoride salts, beryllium or other materials aswell known in the art. The coolant material may be water or oil or anyother suitable fluid serving a cooling/heat extracting function. Heatexchange means 10 may be connected to thermal/electrical orthermal/mechanical power generating equipment.

Also shown in FIG. 1 is a heat exchange means and pump means 12associated with a conduit 14 which passes through the blanket 4 and intothe fusion power core 2. The coolant flowing through conduit 14 servesto cool the field coils utilized to provide the magnetic confinementwithin the fusion power core 2. Only one such conduit 14 is illustratedalthough it is understood that a plurality of conduits may be provided(and a single or an associated plurality of heat exchange means and pumpmeans as required) for cooling various sections of the magnetic fieldcoils. The coolant stream may provide heat energy to heat exchange means12 for utilization in thermal/electrical conversion equipment in orderto produce electrical power therefrom and/or thermal/mechanicalequipment for generation of mechanical (shaft) energy. Thecoolant/thermal extraction system provided by conduits 14 and heatexchange means 12 may be separate and independent from thecoolant/thermal extraction system employed for the blanket 4 oralternately the two systems may utilize common components. Thetemperatures within the coils of the fusion core must be kept below themelting or structurally limiting temperatures of the coil materials(copper or aluminum coils, for example). The heat developed within theblanket 4, however, has no such restriction and the coolant within theblanket may thus be heated to considerably higher temperatures than thecoolant passing through the fusion power core (conduits 14). Thethermal/electrical conversion equipment, for example, associated withthe higher temperature coolant will thus be able to operate at higherthermal/electrical conversion efficiencies than possible for the lowertemperature coolant. For a fusion power core of the toroidal type,coolant is typically provided in the toroidal field coils but may alsobe provided for other field coils if desired (ohmic heating, verticalfield or auxiliary heating coils). Additionally, coolant means similarto that shown by conduits 14 and heat exchange and pump means 12 may beprovided for other regions of the fusion power core, such as a regionbetween the toroidal shell and the toroidal coil as more fully set forthbelow.

An alternate or additional means for cooling and obtaining thermalenergy from the fusion power core 2 and blanket 4 is provided by heatexchange means and pump means 15 together with conduits 16. In thisembodiment, the fluid inflow to module 1 passes between the blanketregions 4a and 4b and is heated by the fusion power core 2 whicheffectively serves to preheat the coolant which is subsequently heatedto higher temperatures by energy from the blanket region 4. In thismanner, a single coolant may be utilized with a singlethermal/electrical conversion unit.

Blanket 4 may also contain a tritium breeding section 17 which maycontain for example lithium utilized to capture neutrons for thebreeding of tritium for subsequent use in the D,T fusion reaction. Heatexchange and pump means 18 together with conduits 20 may be utilized tocool the lithium breeding section 16, or alternately, a molten fluoridesalt of lithium (or lithium plus beryllium, for example) may be used toprovide for tritium breeding as well as self-cooling. Appropriatetritium extraction apparatus 22 is connected to the conduits 20 toextract the tritium for subsequent utilization.

An electrical control means 24 is utilized to provide the current todrive the various field coils within the fusion power core via aplurality of power conductors 26. Thus, in the case of a toroidal ortokamak-type device, conductors 26 serve to provide the necessarycurrent for the toroidal field as well as for the ohmic heatingtransformer, auxiliary heating coils, vertical coils and the like.

The fusion power core 2 is provided with a containment region 28 forhousing the plasma. In the embodiment in which the toroidal-type fusionpower core is utilized, the containment region 28 is simply the toroidalshell or vacuum cavity containing the plasma gas. Means are provided forevacuating the containment region 28 such as by utilizing a vacuum pump30. Gas feeding means 32 are also shown for supplying the fusible fuelor gas to the containment region 28. The gas feeding means 32 maycomprise for example a supply of D,T gas and remotely operable valvemeans for controlling flow of gas into the containment region 28. Eachfusion power core 2 also may be provided with diagnostic ports 33 formeasuring plasma position, density and temperature as is well known inthe art.

As stated below, the fusion power core 2 may be of the tokamak type andinclude the required toroidal magnetic field coils and ohmic heatingcoils. However, it is envisioned that other fusion power cores may beutilized wherein other types of magnetic confinement are obtained, e.g.,stellarator confinement principles, for example. The description hereinis presented in terms of specific embodiment of the tokamak-type fusionreactor and specifically utilizing a D, T fusion reaction process.However, it is clear that other fusion reaction processes, for example,the D,D or D,He³ may be utilized separately, or simultaneously with D,T.

A prime consideration of the present invention is the fact that thefusion power core 2 is removable from the blanket 4 and, in fact, isdisposable, or recyclable. The high temperatures and high fieldsattained in the fusion power core result in an extremely high radiationflux significantly higher than the first well loading heretofore assumedacceptable for practical large scale fusion reactor designs. As a resultof such a high radiation flux on the first wall of the fusion powercore, the fusion power core may deteriorate over a relatively shorttime. In this circumstance, the present invention allows for andprovides a means for replacing the entire fusion power core. Dependingupon specific operating parameters replacement could be required at timeintervals on the order of weeks to months. However, the relatively smallsize of the fusion power core 2 will allow economical means of removaland subsequent disposal and/or reprocessing/recycling thereof andreplacement by a new fusion power core utilizing the same blanket 4.Consequently, the blanket regions 4a and 4b are made separable, and thefusion power core 2 may be removed therefrom. For tokamak-type fusionpower cores, it is possible to reprocess the fusion power core 2 suchthat the copper and other materials within the core may be utilizedagain. As an exemplary conventional frame of reference, assuming a D,Treaction, the fusion power core may have a radius on the order of 1meter and height of approximately 1 meter. Each blanket region maytypically be on the order of 1 meter thick. In practice the exactthickness and shape of the blanket is somewhat arbitrary and may bedesigned to provide adequate thickness for capture of neutrons generatedin the fusion power core. Additionally, the first wall of the blanketshell may be made of high Z or other materials which allow n,2nreactions to enhance blanket neutron yield thus assuring a simpleT-breeding design.

As shown in FIG. 2A, a plurality of modules 1₁ . . . 1_(n), each havinga corresponding blanket 4₁ . . . 4_(n) and cores 2₁ . . . 2_(n) may bearranged together to form a power generating system whereincorresponding coolant conduits 8'₁ . . . 8_(n) are separately connectedto one or more heat exchange and pump means (not shown). An alternatearrangement is shown in FIG. 2B wherein a plurality of modules 1'₁, 1'₂. . . 1'_(n) is shown with series connected coolant conduits 8"₁, 8"₂ .. . 8"_(n). In any such series arrangement, a system bypass means 9 maybe provided so that upon replacement of any individual fusion powercore, the remaining assembly of modules 1' may be left operational. InFIGS. 2A and 2B, the arrows labeled 8'₁, 8'₂ etc. and 8"₁, 8"₂ etc. areused to represent both the blanket coolant/thermal extraction system andcorresponding fusion power core coolant/thermal extraction systemwhether they be separate or integral systems as taught in FIG. 1.Obviously, in FIG. 2B, the fusion power core (blanket) coolant/thermalextraction system could be connected in series with a separate pluralityof blanket (fusion power core) coolant/thermal extraction system for themodules. It is advantageous in these configurations to closely pack themodules 1 together so that neutrons escaping one module may be trappedin an adjacent module thereby increasing overall efficiency.

FIG. 2C shows yet another embodiment of the invention wherein aplurality of fusion power cores are surrounded by a single blanket 34.

FIG. 3 illustrates an electrical power generating system comprising afusion reaction room containing an array of modules 1" such as thoseillustrated in FIG. 2A. Each module in the array is connected to anelectrical supply, gas feeding and vacuum unit in accordance with FIG. 1to supply both the electrical power to each individual fusion power coreand the necessary gas feeding and vacuum pumping means. Alsointerconnected to each of the modules 1" are heat exchange means andconduits which are connected in accordance with elements 8, 10, 12 and14 of FIG. 1 to extract heat from the blanket units as well as toprovide cooling means and heat extraction means for the fusion powercores. A low temperature heat exchange means 42a forms part of thefusion power core coolant/thermal extraction system and is connected toconduit means feeding each fusion power core. For simplicity ofillustration, only one such connecting line is shown. A low temperaturecondenser 44a is connected to the low temperature heat exchange and pumpmeans 42a and to one state of turbine 46. A high temperature heatexchange and pump means 42b forms part of the blanket coolant/thermalextraction system for the modules 1" and is connected to conduit meansfor feeding each blanket. Again, for simplicity of illustration, onlyone such conduit means is illustrated. The high temperature heatexchange and pump means 42b is connected to a high temperature condenser44b and to a second stage of turbine 46. The turbine 46 drives agenerator 48 which supplies electrical energy to an electrical gridworkwhich may in turn be fed by a plurality of units similar to those shownin FIG. 3. Alternatively, instead of or in addition to the electricalconversion one may utilize the turbine 46 to provide mechanical energysuch as shaft rotational energy.

A remotely operable means is also provided for removing any given fusionpower core from its corresponding blanket so that the fusion power coremay be handled, moved, disposed of, or reprocessed to recycle valuablemetals, dispose of radioactive contaminants, and/or to remanufacture andrefabricate an additional (replacement) fusion power core. The remotelyoperable means may comprise remote handling means 51 and a recycle anddisposal means 52. Remote handling means 51 may comprise an overheadcrane and means for connecting and disconnecting the various conduitsand cables feeding the fusion power core 2. A control room 54 is alsoshown for providing a monitor and control means 56 and to provide officespace for personnel. Monitor and control means 56 monitors and controlsthe operation of the entire power generating plant and, in particular,monitors and controls each of the various elements in FIG. 1 shownassociated with module 1. Additionally, plasma position, temperature anddensity may be monitored via diagnostic ports (33 of FIG. 1) in eachmodule 1".

An enlarged top view of a single module 1 is illustrated in FIG. 4. Thefusion power core 2 is shown in cross section. The blanket is shown tobe composed of two regions 4a and 4b which surround the fusion powercore 2. The blanket regions 4a and 4b are also shown in cross sectionbut may not necessarily be taken along the same horizontal plane withrespect to each other. The blanket region 4a is shown permeated with anartery array of conduits 8 which serve to remove thermal energygenerated by neutrons emanating from the fusion power core 2 andabsorbed in the surrounding blanket 4. Although not specificallyillustrated in FIG. 4, the blanket region 4b may similarly contain anarray of conduits for carrying a cooling/thermal energy extractionfluid. The blanket may be comprised of a fluid material instead of themore commonly utilized solid blanket material. If desired, the fluidmaterial may be circulated to serve both as a neutron absorbing mediumand as its own coolant/thermal extraction means, i.e., the fluid may befed via conduits to heat exchange means.

The fusion power core 2 is illustrated in the preferred embodiment ascomprising a tokamak-type reactor wherein plasma is contained in cavityregion 101 of a toroidal shell 100 which may, for example, be composedof aluminum, stainless steel, niobium, molybdenum or the like. The shellmay be in the range of approximately one to a few millimeters thick, andmay be coated internally with beryllium, carbides, graphite or aluminumoxide for protection. The shell may likewise be coated with an aluminumoxide or other insulating layer on the outside thereof for insulation ofthe shell from the surrounding conductors. A series of current carryingconductors or disk coils 102 are disposed around the toroidal shell 100for establishing the toroidal magnetic field. A plurality of spiralgrooves 103 may be provided in the disk coil 102 for passage of acooling fluid therethrough. The grooves 103 communicate with peripheralchannels 103a in the disk coils 102. The coolant fluid passing adjacentthe disk coils 102 may be connected to heat exchange means as shown inFIG. 1 to remove thermal energy therefrom for utilizing same for thegeneration of electric power. Between the disk coil 102 and the shell100 there may be disposed a cooling channel 104 for passage of thecooling fluid around and along the length of the shell 100. The coolingchannel 104 is thus in fluid communication with the spiral grooves 103and peripheral channels 103a. Supporting the shell 100 in the coolingchannel 104 are a plurality of supports 105 which may take the form ofsmall button-like elements or rib members surrounding the toroidalshell.

The cooling channel 104 around the shell 100 (first wall) is utilized tomaintain the shell at controlled temperatures. The channel may typicallybe on the order of one to a few millimeters wide. If necessary forstress and strength considerations, surrounding the disk coils 102 maybe a support means 106 which holds the coils 102 in tension against anouter rib 108 and top and bottom support members 110. The support means106 thus supports the disk coils 102 and shell 100 from the strongforces produced by the generated magnetic fields. Support means 106 maybe fabricated, for example, from steel and may be an integral toroidalunit or a plurality of supports, one for each disk 102. If the supportmeans is integral over two or more disk coils, then insulation means areprovided between the disk coils 102 and support means 106 to preventshorting out of the disk coils. The support member 110 as well as theouter rib 108 may be made of aluminum or other material and aretypically insulated from the support means 106 by insulation means 112(made, for example, of aluminum oxide). Support members 110 are heldtogether by means of a central load carrying member 114 (made ofceramic, for example) as well as by sealed joints 116 at the peripheryof the support means 106.

The fusion power core 2 is provided with ohmic heating coils 120 whichmay take the form of an air core or saturated iron core transformer. Allof the coils illustrated in FIG. 4 are utilized for ohmic heating.Additional auxiliary heating and vertical field coils may also beprovided as more clearly illustrated in reference to FIG. 5 discussedbelow.

Various coolant conduits are provided in the module 1 of FIG. 4 such asfluid conduits 124, 125, 126 and 127. Fluid conduits 124 and 125 areinflow and outflow conduits respectively which are associated with shell100 and disk coil 102. The fluid is passed into the fusion power core 2and circulates in grooves 103 and channels 103a of the disk coils 102and within the cooling channel 104 adjacent and exterior to the shell100. Fluid conduits 126 and 127 are inflow and outflow conduitsrespectively and associated with the ohmic heating coils (as well asvertical and auxiliary heating coils if desired). Thus, conduits 124,125, 126 and 127 form part of the fusion power core coolant/thermalextraction system as disclosed in reference to FIGS. 1 and 3.

In order to facilitate removal of the fusion power core 2 from theblanket 4 for replacement of the fusion power core, the conduits 124-127are passed through coupling means 128 before interconnecting to thefusion power core 2. Coupling means 128 permits easy separation of thefluid conduit sections contained within the fusion power core from theexternal conduits leading to the heat exchange and pump means.Consequently, when the fusion power core is separated from the blanket4, it is only necessary to disconnect the sections of the fluid conduitat the coupling means 128. Functionally similar coupling means 128' areprovided for electrical connections 129 to ohmic heating (OH) coils 120of the fusion power core 2.

The fusible gas, for example, an equal mixture of deuterium and tritiumis fed into the cavity region 101 of shell 100 via a fuel inlet conduit134. Valve means (32 of FIG. 1) are connected to the fuel conduit 134 toregulate the flow of fusible fuel into the plasma cavity region 101. Anextraction fuel conduit 136 is connected to pump means (30 of FIG. 1)and is provided to extract the plasma during the gas purge cycle ofoperation. Both conduits 134 and 136 may be provided with small nozzlemeans to couple to the cavity region 101. Coupling means 128 may also beprovided for the conduits 134 and 136 as shown.

FIG. 4 also illustrates in region 4b of the blanket 4 special fluidpassages 130 for cooling regions 132 containing lithium used forbreeding tritium. The tritium may later be used in the fusion power corefor the D,T fusion reaction. Region 132 may contain, for example, cannedlithium alloys.

A neutron monitor 133 is shown positioned between the fusion power core2 and blanket 4 to provide a means for measuring the reaction rateswithin the plasma. The fusion reaction rate may, of course, beindicative of the plasma temperature or density. The plasma temperaturesmay be determined in a conventional manner as, for example, by utilizinglaser interferometer techniques via the diagnostic port 33 (FIG. 1).

The overall size of the fusion power core 2 in FIG. 4 is quite small incomparison with conventional tokamak designs. In particular, the fusionpower core 2 may have a major radius of approximately 50 centimeters anda minor radius of approximately 20 centimeters. The radial thickness ofthe disk coils 102 is approximately 10 centimeters and each coil mayextend a few centimeters in thickness. One particular coil isillustrated in FIGS. 5, 5A and 5B and employs cooling grooves 103' inthe form of radial grooves which may alternately be used instead of thespiral grooves shown in FIGS. 4 and 6. One portion of the disk coil isbent outwardly for alignment with the adjacent disk coil around thetoroidal shell 100. The disk coils 102 are arranged around the plasmashell 100 and are placed adjacent to each other to form a complete coilproducing the toroidal field. It is contemplated that 176 such diskcoils may be utilized either series connected or connected in modulargroups such that there are 8 separate coils per each coil group with atotal of 22 coil groups. In such an arrangement each coil group wouldcomprise one complete turn and would be electrically connected to thenext coil group to form a series current path through the entireplurality of coils.

FIG. 6 illustrates an enlarged sectional view of part of the fusionpower core as shown in FIG. 4. Fluid conduits 124 and 126 and fuelconduit 134 have already been discussed in relation to FIG. 4. Variousfield coils are shown in FIG. 6 in addition to the OH coils 120. Forexample, field coils 142 may be used to provide a vertical field (VF)for positioning the plasma, and coils 144 may be used, if desired, asauxiliary heating coils. Auxiliary heating of the plasma may, of course,be provided by other means such as ripple currents on the VF coils 142,microwave techniques etc.

FIG. 7 illustrates a cross-sectional view of the fusion power coreshowing the disk coils 102 and support means 106 as taken along line7--7 of FIG. 6. Ohmic heating coils and conduits are now shown forsimplicity of illustration. FIG. 7 shows the disk coils 102 with anintegral support means 106'. Support means 106' is shown broken away sothat the disk coils 102 may be more clearly seen. Each disk coil 102 iswedged-shaped and separated by an insulation means 152 which may takethe form of a thin ceramic disk. The insulation means 152 mayalternately be provided by an insulating coating on the disk coils 102.FIG. 7A illustrates the disk coils 102 with separate support means 106,one such support means associated with each disk coil 102.

FIG. 8 is a side plan view of a module 1 wherein the fusion power core 2is being removed from the blanket regions 4a and 4b by an overhead crane160 forming part of the remote handling means 51. The blanket regions 4aand 4b are carried on support means such as a remotely operable trolley168 for separating the blanket regions to allow removal of the fusionpower core 2. For ease of illustration, various fluid conduits, gas andvacuum feed lines and electrical connection lines are not shown. Thecrane 160 lifts the fusion power core 2 from a support means 170 andmoves it to the recycle and disposal means 52 (FIG. 3) for processing. Anew or recycled fusion power core 2 is then placed on the support means170 via the overhead crane 160 and the fluid conduit, gas feed andvacuum lines as well as electrical connections are connected via theremote handling means 51 to the new fusion power core 2.

The fusion power core may be driven to ignition and thence to powerproducing levels in cycles utilizing gas staging techniques as describedin copending application Ser. No. 755,794 filed Dec. 30, 1976 and/orutilizing e-beam techniques as described, for example in U.S. Pat. No.3,831,101 incorporated herein by reference.

In practice, each fusion power core 2 of FIG. 3 is cycled through aninitial start-up stage, ignition stage and burn stage so that theresidual gas in the plasma cavity 101 may be pumped out and a new gasmixture introduced at the beginning of stage 1. Power is switched intoeach fusion power core 2 in a sequential manner by means of theelectrical supply units 40 and monitor and control means 56 of FIG. 3.For example, assume that there are 20 fusible power core units operatingat a "burn time" of 25 seconds with a 30-second total cycle time. Thecontrol means for the power system activates unit 1 associated with thefirst fusion power core. Approximately 1.5 seconds later (30/20) poweris supplied to unit 2 while continuing power to unit 1. Three secondslater, unit 3 is switched on while continuing power to units 1 and 2,etc., until all units are being driven at the 30-second cycle time. Inthis manner, an average power output may be supplied by the generator48. It is expected, of course, that not all of the fusion power coreswill need replacement at the same time. The replacement of any givenfusion power core is thus made as required, but because of the smallsize and simplicity of the replacement procedure such replacement takesa relatively short time and does not require shutdown of other fusionpower cores. Consequently, such replacement will not appreciably affectthe overall power output of the generating plant.

While the invention has been described in reference to the preferredembodiments set forth above, it is evident that modifications andimprovements may be made by one of ordinary skill in the art, and it isto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically set forthherein.

I claim:
 1. A toroidal reactor for generating thermal energy from fusionreactions in ionized plasma of fusible fuel comprising:(a) fusion coreunit comprising a plasma containment means having a major radius on theorder of 50 cm for containing said fusible fuel, said plasma containmentmeans forming a plasma containment region, (b) said plasma containmentmeans including a plurality of toroidal field coils adjacent to andsurrounding said plasma containment region for generating a toroidalmagnetic field, (c) means for transporting a cooling fluid to saidtoroidal field coils, (d) said toroidal field coils having fluidconducting portions for transporting said cooling fluid within regionsof said toroidal field coils, (e) power supply means connected to saidtoroidal field coils for generating a high toroidal magnetic fieldwithin the ionized plasma within said plasma containment region, saidtoroidal magnetic field being on the order of greater than 100 KG, (f)said plurality of toroidal field coils comprising high-strength;non-superconducting conductors for sustaining said high field andthermal energies, (g) ohmic heating means for inducing an ohmic heatingplasma current in said plasma fuel within said plasma containment means,said ohmic heating current raising the temperature of said plasma, saidohmic heating means including transformer means and said ohmic heatingcurrent generating a poloidal magnetic field within said plasma, (h)blanket means positioned completely outside of and substantiallysurrounding said toroidal field coils, (i) means extending into saidplasma containment means for delivering said fusible fuel therein, (j)said fusion core unit being readily separable from said blanket meansfor permitting facile access to said fusion core unit to allow forreplacement of said fusion core unit as required, (k) blanket coolingfluid transport means connected to said blanket means for transporting acooling fluid to said blanket means, and (l) means connected to at leastone of said blanket cooling fluid transport means and said toroidalfield cooling transport means for extracting thermal energy therefrom.2. The toroidal reactor of claim 1, wherein said plasma containmentmeans further includes a toroidal housing having a major radius on theorder of 50 cm and a minor radius on the order of 20 cm and wherein,said toroidal field coils being adjacent to and surround said toroidalhousing and means for transporting said cooling fluid around thesurfaces of said toroidal housing adjacent said toroidal field coils. 3.The toroidal reactor of claim 2, wherein said blanket means furtherincludes tritium breeding means for generating tritium from neutronsemitted in said fusion reactions.
 4. A toroidal reactor as recited inclaim 1 wherein said plasma containment means comprises:(a) a toroidalregion for containing said plasma, and (b) means, including saidplurality toroidal field coils, for magnetically confining said plasmawithin said toroidal region.
 5. A toroidal reactor as recited in claim 4wherein said means for magnetically confining said plasma furthercomprises means, in addition to said ohmic heating means, for generatingsaid poloidal magnetic field.
 6. A toroidal reactor as recited in claim1 or 5 wherein said toroidal magnetic field strength is on the order of100-150 kilogauss.
 7. A toroidal reactor as recited in claim 1 whereinsaid fusible fuel is a mixture of deuterium and tritium.
 8. A toroidalreactor as recited in claim 7 wherein said means for extracting thermalenergy is connected to both said plasma containment means and saidblanket means and comprises fluid transport means.
 9. A toroidal reactoras recited in claim 8 wherein said thermal energy extraction meanscomprises one fluid transport means for extracting thermal energy fromsaid plasma containment means and another fluid transport means forextracting thermal energy from said blanket means.
 10. A toroidalreactor as recited in claim 8 wherein said thermal energy extractionmeans comprises a single fluid transport means for both said plasmacontainment means and said blanket means.
 11. A toroidal reactor asrecited in claim 6 wherein said fusible fuel is a mixture of deuteriumand tritium.
 12. A toroidal reactor as recited in claim 1 wherein saidmeans for extracting thermal energy is connected to both said plasmacontainment means and said blanket means and comprises fluid transportmeans.
 13. A toroidal reactor as recited in claim 12 wherein saidthermal energy extraction means comprises one fluid transport means forextracting thermal energy from said plasma containment means and anotherfluid transport means for extracting thermal energy from said blanketmeans.
 14. A toroidal reactor as recited in claim 12 wherein saidthermal energy extraction means comprises a single fluid transport meansfor both said plasma containment and said blanket means.
 15. A toroidalreactor as recited in claim 1 wherein said fusible fuel is a mixture ofdeuterium and tritium, said plasma containment means comprising atoroidal region and said toroidal region having a major radius on theorder of 50 cm.
 16. A toroidal reactor as recited in claim 15 whereinsaid toroidal region has a minor radius on the order of 20 cm.
 17. Atoroidal reactor as recited in claim 1 wherein said plasma containmentmeans includes a toroidal region having as aspect ratio of approximately2.5.
 18. A toroidal reactor as recited in claim 17 wherein said toroidalfield coils include copper-coils.
 19. A toroidal reactor as recited inclaim 1 further comprising means for reprocessing said radiation-damagedcontainment means.
 20. A toroidal reactor device as recited in claim 1further comprising auxiliary heating means for heating said plasma.